The purpose of this project is to develop and test the feasibility of a combined internet and wireless SMS text messaging application to deliver a self-help behavioral smoking cessation program based on scheduled gradual reduction of smoking. The Phase I prototype will allow the user to personalize and tailor the cessation program via web interface. The web site also will provide cessation training modules not easily delivered in limited text messaging formats. Once personalized, the program will be delivered via any communication device with SMS capabilities (e.g. most cell phones, alphanumeric pagers, wireless email devices). The program will assess baseline smoking using a sampling procedure with iterative mean calculations until a stable baseline is obtained. The program will then prompt the user to smoke using a scheduled gradual reduction algorithm. Social support and coping strategy messages also will be sent to the user based on personalization data and progress during the reduction. Once cessation is achieved, the program will provide relapse prevention messages. After development and testing of the Phase I prototype, feasibility testing will be performed on 50 smokers in a 10-week open trial using the program delivered on their personal cell phones or other SMS devices. Feasibility criteria will include program utilization, subjective ratings of various features, and reductions in nicotine dependence, as well as seven day point prevalence abstinence at post-treatment, validated via CO and saliva cotinine. Using SMS technology, a behavioral smoking cessation intervention can be delivered in real time and in the context in which the urges to smoke occur. Given the growing penetration rate of cell phone users in the U.S., nearly all with text messaging capabilities, this program has the potential to impact a large number of current smokers and provide a low cost, easily disseminated behavioral smoking cessation intervention.